Suspension flow control apparatus

ABSTRACT

Apparatus for controlling the rate of flow of fluid-solid suspension from a higher pressure source to a lower pressure receiver through a conduit, comprising a pressure reduction chamber interposed in the conduit intermediate upstream and downstream portions thereof, and a rotor operatively associated with the chamber whereby its driven rotation causes recirculatory flow of suspension in the chamber. The chamber is connected to the conduit upstream portion by a peripheral inlet to receive the suspension outwardly of the periphery of the rotor and connected to the conduit downstream portion through an outlet axially of the rotor to discharge the suspension axially of the latter. The apparatus is particularly suited for application in controlling the flow of liquid-solid suspensions such as rejects suspensions from fractionating apparatus of the type employed for the separation of knots and other coarse material during the processing of paper making pulp.

United States Patent [191 Young [111 3,928,187 Dec. 23, 1 975 SUSPENSION FLOW CONTROL APPARATUS [75] Inventor: Douglas L. G. Young, Lennoxville,

Canada [73] Assignee: Canadian Ingersoll-Rand Company Limited, Montreal, Canada [22] Filed: Nov. 13, 1974 [21] Appl. No.: 523,345

[52] US. Cl. 209/255; 209/273; 415/213 A [51] Int. Cl. B07B 1/18 [58] Field of Search 209/255, 270, 273, 300, 209/303-306; 210/407; 415/213 A [56] References Cited UNITED STATES PATENTS 689,934 12/1901 Vruuman 2091270 2,021,797 12/1952 Smith 210/407 X 2,432,247 12/1947 McAngllen 415/120 X 2,835,173 5/1958 Martindale.. 209/270 X 3,255,883 6/1960 Ne1son.... 209/273 X 3,647,067 3/1972 Vogel 209/273 X R24,803 3/1960 Burnside.... 415/213 A I 7 56 IO l r EL. 56 3- 3 i -4 L 1 /,46 Ja a Primary Examiner-Robert Halper Attorney, Agent, or Firm-Robert R. Paquin [57] ABSTRACT Apparatus forcontrolling the rate of flow of fluidsolid suspension from a higher pressure source to a lower pressure receiver through a conduit, comprising a pressure reduction chamber interposed in the conduit intermediate upstream and downstream portions thereof, and a rotor operatively associated with the chamber whereby its drivenrot ation causes recirculatory flow of suspension in the chamber. The chamber is connected to the conduit upstream portion by a peripheral inlet to receive the suspension outwardly of the periphery of the rotor and connected to the conduit downstream portion through an outlet axially of the rotor to discharge the suspension axially of the lat,- ter. The apparatus is particularly suited for application in controlling the flow of liquid-solid suspensions such as rejects suspensions from fractionating apparatus of the type employed for the separation of knots and other coarse material during the processing of paper making pulp.

13 Claims, 4 Drawing Figures US. Patent Dec. 23, 1975 3,928,187

SUSPENSION FLOW CONTROL APPARATUS The present invention relates to apparatus for con trolling the rate of flow of a fluid-solid suspension from a higher pressure source to a lower pressure receiver and more specifically to apparatus of this general type particularly suited for control of a liquid-solid suspension containing relatively large or coarse solid material.

Conventionally, it has been frequently difficult to provide such flow control of liquid-solid suspensions containing relatively large or coarse solid material. For example, it has been difficult to effectively control the flow rate of the rejects or rejected liquid-solid suspension discharged from a relatively high pressure fractionator or de-knotter employed for separating knots and other coarse material during the processing of paper making pulp, due to the relatively large size of the solid material or knots contained in such rejects suspension. Attempts to provide this flow control by employment of valving in the rejects discharge conduit have been unsatisfactory as the knots tend to jam the valve port and obstruct the movement of the valving element. Attempts to provide this flow control without valving in the rejects discharge conduit, generally have involved the provision of valving in the accepts discharge conduit and accompanying arrangement of the discharge end of the rejects discharge conduit at a suitably high elevation. This latter arrangement, although generally satisfactory in application with relatively low pressure fractionating apparatus, is inherently unsuitable for employment with fractionating apparatus operating at higher pressure as the elevation at which the rejects discharge conduit must discharge increases with increases in the pressure maintained in the fractionating apparatus.

An object of the present invention is to provide new and improved apparatus particularly adapted for controlling the rate of flow of a fluid-solid suspension from a higher pressure source to a lower pressure receiver.

Another object of the invention is to providenew and improved apparatus of the type set forth particularly adapted for employement with a liquid-solid suspension containing larger solid material, such as, for example, the rejects suspension discharged from the beforementioned fractionating apparatus.

Another object is to provide new and improved apparatus of the type set forth particularly adapted to provide such control without the necessity for valving in the conduit conveying the suspension.

Another object is to provide new and improved apparatus of the type set forth particularly adapted for application with suspensions at higher pressure than feasible with the beforedescribed conventional arrangements including valving in the accepts discharge conduit.

Another object is to provide new and improved apparatus of the type set forth which, although particularly suited for employment with liquid-solid suspensions of the beforementioned type, is capable of alternative employment with other fluid-solid suspensions.

Other objects and advantages of the invention will become apparent from the following description taken in connection with the accompanying drawings wherein, as will be understood, the preferred embodiments of the invention have been given by way of illustration only.

In accordance with the invention there may be provided, in combination, a pressurized source of fluidsolid suspension, a receiver for the suspension at lower pressure than the source, conduit means interconnecting the source with the receiver for supplying suspension from the source to the receiver, and pressure reducing means operatively associated with the conduit means for reducing the pressure of suspension flowing from the source to the receiver through the conduit means whereby the rate of such suspension flow is thereby reduced, the pressure reducing means comprising chamber means interposed in the conduit means intermediate upstream and downstream portions thereof, rotor means operatively associated with the chamber means to cause its driven rotation to provide recirculatory flow of suspension within the chamber means, and driving means operatively connected to the rotor means for rotatablydriving the rotor means, the chamber means having peripheral inlet means communicating with the source through the upstream 'portion of the conduit means for introducing suspension from the source into the chamber means adjacent the periphery thereof, and the chamber means having outlet means centrally of the rotor means connected to the receiver through the downstream portion of the conduit means for discharging suspension from the chamber means to the receiver.

Referring to the drawings:

FIG. 1 is an elevational view, partially broken away and in section, schematically illustrating an embodiment of the invention in acompaniment with a fractionating apparatus of the type suitable for the beforementioned de-knotting;

FIG. 2 is a substantially enlarged, elevational sectional view of the embodiment of the invention shown in FIG. 1;

FIG. 3 is an elevational view, taken along Line 33 in FIG. 2 looking in the direction of the arrows,showing the rotor or impeller of such embodiment of the invention; and

FIG 4 is a fragmentary elevational view, partially broken away and in section, of an alternative embodiment of the invention in combination with a fractionating apparatus such as shown in FIG. 1.

Referring more particularly to the drawings wherein similar reference characters designate corresponding parts throughout the several views, FIG. 1 illustrates a fractionating apparatus, designated generally as 10, which, per se, is of the type described in US. Pat. No. 3,814,244, issued June 4, 1974 and assigned to the assignee of the present invention. As will be understood, however," the illustrated fractionating apparatus 10 has been shown for the purposes of illustration only and the invention is not limited to application-with the apparatus 10, but rather may be alternatively employed with other suitable sources of pressurized fluid-solid suspension.

The fractionating apparatus 10 comprises a generally vertical, pressurized casing 12 ground mounted by a base 14. Adjacent to its upper end, the casing 12 includes a tangential inlet 16 which is connected to a pressurized source (not shown) of the liquid-solid suspension (hereinafter called inlet suspension) to be fractionated; and the upper end of the casing 12 .contains a generally annular inlet gutter l8 communicating with the inlet 16 to continuously receive the inlet suspension from such source. Adjacent to its lower end, the casing 12 includes an accepts outlet 20 and a re- 3 jects outlet 22, the accepts outlet 20 being connected to conventional piping (not shown) arranged to discharge the accepts or accepted liquid-solid portion (hereinafter called accepts suspension) of the inlet suspension from the apparatus 10. The rejects outlet 22 is connected to one end of a rejects discharge conduit 24 which at its other end is connected to a receiver 26 at substantially lower pressure than the pressure normally maintained within the casing 12 adjacent to the rejects outlet 22, whereby the rejects or rejected liquidsolid portion (hereinafter called rejects suspension) of the inlet suspension discharged from 'the apparatus during its operation flows from the outlet 22 to the receiver 26 through the conduit 24. An annular screen or screen plate 28, including openings adapted to separate the accepts suspension from the rejects suspension, is movably disposed within the .casing 12 on a generally vertical axis. The screen 28 is radially spaced from the surrounding wall 30 of the casing 12 by an annular screening passage 32 which at its upper end is open to communication with the inlet gutter l8 and at its lower end communicates through an annular. rejects chamber 34 with the rejects outlet 22nwhereby, during operation of the apparatus .10, inlet suspension flows from the inlet gutterl8 to the upper end of the screening passage 32 and rejects suspension is discharged from the lower end of the screening passage 32 to the rejects chamber 34 and rejects outlet 22. An imperforate, annular, stationary wall member 36 is disposed concentrically within the screen 28. radially spaced from the latterby an annular accepts space or passage 38 which at its lower end communicates with an annular accepts chamber 40, in turn, communicating with the accepts outlet 20. Theapparatus 10 further includes a screen driving means in the form of a rotatable drive shaft, designated generally -as 42,.at its lower end including a portion 44 connected to a rotary output driving motor 46 through abelt drive 48. The drive shaft 42 includes an upper portion 50, integral with the lower portion 44, which has its longitudinal axis eccentric to, or offset from, the lower portion 44. The eccentric portion 50 is connected by bearings 52 to the screen 28 to orbitally drive the latterrelative to the casing wall 30 and the wall 36 duringthedrive n rotation of the drive shaft 42, rotation of the screen 28 during such orbital movementbeing restrained bylresilient sleeves 54 and the forces generated during the operation of the apparatus 10 being countered by balancing weights 56 affixed to the drive shafti42. Further details of the construction of the fractionating appara- ,tus 10, if desired, can be obtained from the beforemen tioned US. Pat; No. 3,814,244.,

= In accordance with the invention, an'apparatlis, designated generally as 58, is interposed in the rejects discharge conduit 24,, intermediate upstream and downstream portions 60, 62, res ectively, of the latter, for substantiallyreducing the pressure )of the rejects suspension flowing from the apparatus 10 to the receiver '26 through the conduit 24 whereby the rate of such rejects suspension flow is resultaritly \thereby substantially reduced from what it would'otherwise be in the absence of the apparatus 58. Broadly-considered, the apparatus 58 is in the form of a pump having its inlet and outlet connections reversed from the normal that is, having its normal outlet connected to the conduit upstream portion 60 to serve an an inlet, and its normal inlet connected to the conduit downstream portion 62 to serve as an outlet.

More particularly, the illustrated apparatus 58 comprises a volute housing or casing 64 containing a pressure reduction chamber 66 which is peripherally bounded by an annular wall 68 and along opposite sides bounded by side walls 70, 72. A rotor or impeller, designated generally as 74, is disposed in a recess 90 in the side wall 72 to be located entirely outside of the pressure reduction chamber 66, but operatively associated therewith whereby its driven rotation creates recirculatory flow of rejects suspension in the chamber 66 to generate high shear gradients therein. The rotor or impeller 74 is of the open type having no front shroud and comprises a hub 76, a rear shroud 78 and a plurality of vanes 80. The rotor 74 is connected to be rotatably driven by a variable speed driving means shown as comprising a conventional rotary output driving motor 82 and a conventional variable speed drive transmission 84 through which the motor 82 is drivingly connected to rotate the rotor 74. Alternatively to this arrangement, however, the rotor 74 could be driven by a variable speed driving motor. The rotor 74 may moreover be located within the pressure reduction chamber, rather than external thereto, in applications of the invention in which the solids in the suspension v are of relatively small size.

through the wall 70 co-axially of the rotor 74, which is connected to the downstream portion 62 of the rejects conduit 24 for discharging suspension from the chamber 66 centrally of the rotor 74 to the receiver 26.

Throughout the operation of the beforedescribed apparatus, the drive shaft 42 of the fractionating apparatus 10 is continuously rotatably driven by its driving motor 46 to provide continuous orbital movement of thescreen 28. Pressurized liquid-solid inlet suspension to be fractionated by the apparatus 10 (that is, a pressurized suspension, containing knots and other coarse material, in the embodiment of FIGS. 1 through 3) is continuously introduced into the casing 12 through the inlet 16 and passes downwardly to the screening passage 32 where the screen 28 continuously separates it into accepts suspension passing inwardly through the screen openings and rejects suspension passing down wardly to the rejects chamber 34. The accepts suspension continuously flows to the accepts chamber 40 and is discharged from the apparatus 10 through the acceptsoutlet 20. The rejects suspension continuously flows from the rejects chamber 34 through the rejects outlet 22 into the upstream portion 60 of the rejects discharge conduit 24. The pressure of the suspension in thescreening passage 32, and also the pressure of the rejects suspension discharged through the rejects outlet 22, are, as conventional, substantially greater than the pressure maintained within the receiver 26.

The rejects suspension passes through the conduit upstream portion 60 and is tangentially introduced by the inlet 86 into the pressure reduction chamber 66 of the apparatus 58 adjacent to the periphery of the chamber 66. The rotor 74, being continuously rotatably driven throughout the operation of the apparatus in the clockwise direction schematically depicted by the arrow, shown peripherally of the rotor 74 in FIG. 3,

generates pressure against the flow of rejects suspension through the inlet 86 and causes recirculatory flow of rejects suspension in the chamber 66 to generate high shear gradients in such suspension within the chamber 66. (The recirculatory flow believed to occur 5 in the chamber 66, is schematically depicted by the arrows shown in the chamber 66 in FIGS. 2 and 3.) Hence, the rotor 74 dissipates the energy of the rejects suspension flow and reduces the pressure of the rejects suspension; and the flow rate of the rejects suspension is thereby substantially reduced as compared with what it would otherwise be in the absence of the apparatus 58. Furthermore, by either manual or automatic variation of the speed at which the rotor 74 is rotatably driven by its beforedescribed variable speed driving means, selective variation of the magnitude of this pressure reduction may be readily accomplished. The rejects suspension, at such substantially reduced pressure and flow rate, is discharged from the pressure reduction chamber 66 through the outlet 88 to the downstream portion 62 of the rejects conduit 24 which conveys it to the receiver 26.

FIG. 4, wherein parts corresponding to those beforedescribed are designated by the similar reference numeral followed by the suffix a, illustrates an alternative embodiment of the invention in the form of an apparatus a which is directly connected to the lower portion 44a of the drive shaft 42a of the fractionating apparatus whereby the rotor 74 is directly driven thereby. The operation of the FIG. 4 embodiment is identical to that of the embodiment of FIGS. 1 through 3 except that the rotor 74a is so directly rotatably driven by the drive shaft 420 rather than rotatably driven by a separate driving means through a variable speed drive transmisssion.

From the preceding description, it will be seen that the invention provides new and improved means for attaining all of the beforedescribed objects and advantages. It will be understood, however, that, although only a few embodiments of the invention have been illustrated and hereinbefore specifically described, the invention is not limited merely to these few embodiments but rather contemplates other embodiments and variations within the scope of the following claims.

Having thus described my invention, 1 claim:

1. In combination, a pressurized source of fluid-solid suspension, a receiver for said suspension at lower pressure than said source, conduit means interconnecting said source with said receiver for supplying suspension from said source to said receiver, and pressure reducing means operatively associated with said conduit means for reducing the pressure of suspension flowing from said source to said receiver through said conduit means, said pressure reducing means comprising chamber means interposed in said conduit means intermediate upstream and downstream portions thereof, rotor means operatively associated with said chamber means to cause its driven rotation to provide recirculatory flow of suspension within said chamber means, and driving means operatively connected to said rotor means for rotatably driving said rotor means, said chamber means having peripheral inlet means communicating with said source through said upstream portion of said conduit means for introducing suspension from said source into said chamber means adja- Cent the periphery thereof. and said chamber means having outlet means centrally of said rotor means connected to said receiver through said downstream por tion of said conduit means for discharging suspension from said chamber means to said receiver.

2. The combination of claim 1, wherein said inlet means comprises a tangential inlet.

3. The combination of claim 1, wherein said rotor means comprises an open impeller.

4. The combination of claim 1, wherein said inlet means comprises means for supplying the suspension into said chamber means outwardly of the periphery of said rotor means.

5. The combination of claim 1, wherein said rotor means is external to said chamber means.

6. The combination of claim 1, wherein said driving means comprises means for rotatably driving said rotor at variable speeds.

7. The combination of claim 1, wherein said inlet means comprises a tangential inlet for introducing the suspension into said chamber means outwardly of the outer periphery of said rotor means, said rotor means comprises an open impeller, and said driving means comprises means for rotatably driving said rotor means at variable speeds.

8. The combination of claim 7, wherein said impeller means is external to said chamber means.

9. In combination, a pressurized fractionating apparatus including screen means for separating a liquidsolid suspension into a liquid-solid accepts suspension passing through said screen means and a liquid-solid rejects suspension rejected by said screen means, said fractionating apparatus further including outlet means for discharging said rejects suspension separately from said accepts suspension, a receiver for said rejects suspension at lower pressure than said outlet means, con.- duit means interconnecting said outlet means of said fractionating apparatus with said receiver for supplying said rejects suspension to said receiver, and pressure reducing means operatively associated with said conduit means for reducing the pressure of said rejects suspension flowing from said fractionating apparatus outlet means to said receiver through said conduit means, said pressure reducing means comprising means defining pressure reduction chamber means interposed in said conduit means intermediate upstream and downstream portions thereof, rotor means operatively associated with said chamber means for generating pressure against the flow of rejects suspension to said receiver and providing recirculatory flow of rejects suspension within said chamber means, and driving means connected to said rotor means for rotatably driving said rotor means, said chamber means having peripheral inlet means communicating with said fractionating apparatus outlet means through said upstream portion of said conduit means, and adapted to supply rejects suspension to said chamber means outwardly of the outer periphery of said rotor means, and said chamber means having outlet means axially of said rotor means communicating with said receiver through said downstream portion of said conduit means.

10. The combination of claim 9, wherein said inlet means comprises a tangential inlet.

11. The combination of claim 9, wherein said rotor means comprises an open impeller.

12. The combination of claim 9, wherein said rotor means is external to said chamber means.

13. The combination of claim 9, wherein said driving means comprises means for rotatably driving said rotor means at variable speeds. 

1. IN COMBINATION, A PRESSURIZED SOURCE OF FLUID-SOLID SUSPENSION, A RECEIVER FOR SAID SUSPENSION AT LOWER PRESSURE THAN SAID SOURCE, CONDUIT MEANS INTERCONNECTING SAID SOURCE WITH SAID RECEIVER FOR SUPPLYING SUSPENSION FROM SAID SOURCE TO SAID RECEIVER, AND PRESSURE REDUCING MEANS OPPERATIVELY ASSOCIATED WITH SAID CONDUIT MEANS FOR REDUCING THE PRESSURE OF SUSPENSION FLOWING FROM SAID PRESSURE REDUCING MEANS COMPRISING CONDUIT MEANS, SAID PRESSURE REDUCING MEANS COMPRISING CHAMBER MEANS INTERPOSED IN SAID CONDUIT MEANS INTERMEDIATE UPSTREAM AND DOWNSTREAM PORTIONS THEREOF, ROTOR MEANS OPERATIVELY ASSOCIATED WITH SAID CHAMBER MEANS TO CAUSE ITS DRIVEN ROTATION TO PROVIDE RECIRCULATORY FLOW OF SUSPENSION WITH SAID CHAMBER MEANS, AND DRIVING MEANS OPERATIVELY CONNECTED TO SAID ROTOR MEANS FOR ROTATABLY DRIVING SAID ROTOR MEANS, SAID CHAMBER MEANS HAVING PERIPHERAL INLET MEANS COMMUNICATION WITH SAID SOURCE THROUGH SAID UPSTREAM PORTION OF SAID CONDUIT MEANS FOR INTRODUCING SUSPENSION FROM SAID SOURCE INTO SAID CHAMBER MEANS ADJACENT THE PERIPHERY THEREOF, AND SAID CHAMBER MEANS HAVING OUTLET MEANS CENTRALLY OF SAID ROTOR MEANS CONNECTED TO SAID RECEIVER THROUGH SAID DOWNSTREAM PORTION OF SAID CONDUIT MEANS FOR DISCHARGING SUSPENSION FROM SAID CHAMBER MEANS TO SAID RECEIVER.
 2. The combination of claim 1, wherein said inlet means comprises a tangential inlet.
 3. The combination of claim 1, wherein said rotor means comprises an open impeller.
 4. The combination of claim 1, wherein said inlet means comprises means for supplying the suspension into said chamber means outwardly of the periphery of said rotor means.
 5. The combination of claim 1, wherein said rotor means is external to said chamber means.
 6. The combination of claim 1, wherein said driving means comprises means for rotatably driving said rotor at variable speeds.
 7. The combination of claim 1, wherein said inlet means comprises a tangential inlet for introducing the suspension into said chamber means outwardly of the outer periphery of said rotor means, said rotor means comprises an open impeller, and said driving means comprises means for rotatably driving said rotor means at variable speeds.
 8. The combination of claim 7, wherein said impeller means is external to said chamber means.
 9. In combination, a pressurized fractionating apparatus including screen means for separating a liquid-solid suspension into a liquid-solid accepts suspension passing through said screen means and a liquid-solid rejects suspension rejected by said screen means, said fractionating apparatus further including outlet means for discharging said rejects suspension separately from said accepts suspension, a receiver for said rejects suspension at lower pressure than said outlet means, conduit means interconnecting said outlet means of said fractionating apparatus with said receiver for supplying said rejects suspension to said receiver, and pressure reducing means operatively associated with said conduit means for reducing the pressure of said rejects suspension flowing from said fractionating apparatus outlet means to said receiver through said conduit means, said pressure reducing means comprising means defining pressure reduction chamber means interposed in said conduit means intermediate upstream and downstream portions thereof, rotor means operatively associated with said chamber means for generating pressure against the flow of rejects suspension to said receiver and providing recirculatory flow of rejects suspension within said chamber means, and driving means connected to said rotor means for rotatably driving said rotor means, said chamber means having peripheral inlet means communicating with said fractionating apparatus outlet means through said upstream portion of said conduit means, and adapted to supply rejects suspension to said chamber means outwardly of the outer periphery of said rotor means, and said chamber means having outlet means axially of said rotor means communicating with said receiver through said downstream portion of said conduit means.
 10. The combination of claim 9, wherein said inlet means comprises a tangential inlet.
 11. The combination of claim 9, wherein said rotor means comprises an open impeller.
 12. The combination of claim 9, wherein said rotor means is external to said chamber means.
 13. The combination of claim 9, wherein said driving means comprises means for rotatably driving said rotor means at variable speeds. 